Truly as a resident in d states ,i can authoritatively tell you that u can renew ur passports at any nigerian consulate/embassy abroad!!!!..Am pretty 100% sure..but its going to cost u little money..
But mr man,u dey surprise me oooooooo!!!!...Didnt u read ur Passport booklet...Hum...naija man!!! for heavens sake its written on ur passport that u can reknew expiring passports at consulates abroad...U don't even know what u are holding

...The reknewal isnt a big deal,the consulate will just inkstamp ur passport showing its been renewed...Chikena